Method of forming stitched end closures for paper bags



Aug. 1; 1961 A. F. OTTINGER 2,994,631

METHOD OF FORMING STITCHED END CLOSURES FOR PAPER BAGS Filed June 6, 1956 United States Patent 2,994,631 METHOD OF FORMING STITCHED END CLOSURES FOR PAPER BAGS August F. Ottinger, St. Louis, Mo., assignor to Bemis Bro. Bag Company, St. Louis, Mo., a corporation of Missouri Filed June 6, 1956, Ser. No. 589,669 4 Claims. (Cl. 154-116.5)

This invention. relates to methods of forming bag closures, more particularly stitched end closures for paper bags.

Among the several objects of the invention may be noted the provision of a method of forming an improved stitched end closure construction for paper bags having novel means for reinforcing the closure and preventing sifting of the bag contents (such as cement or fertilizer) through the needle holes made by the stitching; the provision of a method of forming a closure of the class described in which the stated means is also effective to prevent scufling of the stitching thread and also to lock the thread in place in case of a skipped stitch or stitches, as may sometimes occur; the provision of a method of forming a closure of the class described which is unaffected by climatic changes; and the provision of a method of forming a closure of the class described adapted for the quantity production of bags. In general, the method of this invention comprises folding a paper tape around the end of the bag, driving a line of stitching through the tape and the walls of the bag, applying a separate strip of heat-scalable plastic over the stitching at least on one side of the folded tape extending from side-to-side of the bag, and applying heat and pressure to the strip to heat seal it throughout its length to the tape on opposite sides of the stitching, and to cause portions of the plastic material of the strip to extend into and plug the needle holes made by the stitching. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the methods hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. 1 is a view in elevation of one side of an end portion of a bag provided with a closure of this invention;

FIG. 2 is a view of the other side of FIG. 1; and,

FIGS. 3 and 4 are greatly enlarged cross sections taken on lines 3-3 and 44 of FIG. 1.

Corresponding reference characters indicate corresponding parts through the several views of the drawings.

Referring to the drawings, there is indicated at 1 in FIGS. 1 and 2 a portion of a paper bag having at 3 a closure of this invention. The bag is shown as having gussets 5 but it will be understood that it may be a flat (ungusseted) bag. Usually the bag will be a multi-ply paper bag of conventional construction other than the closure 3.

The closure 3 comprises a paper tape 7 folded around the end of the bag and secured to the bag by adhesive A. A line of stitching 9 is driven through the tape and through the walls of the tube. As herein illustrated, the stitching comprises a needle thread 11 having loops 13 extending from one side of the bag through the tape and through needle holes 15 in the bag walls, and a looper thread 17 on the other side of the bag securing the loops from pulling out through the needle holes. It will be understood that the needle holes are made in the bag as a result of driving the needle through the bag walls to carry the loops 13 through the walls. The stitching may be of the conventional chain stitch or lock stitch type. It may also be a single-thread type of stitching, instead of a two-thread type.

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In accordance with this invention, a strip 19 of flexible heat-scalable sheet plastic material such as polyethylene is applied to the tape 7 over the needle thread 11 on the needle side of the bag. This strip extends from one side of the bag to the other and is heat sealed throughout its length to the tape on opposite sides of the needle thread. A similar strip 21 of flexible heat-scalable sheet plastic material such as polyethylene is also shown as applied to the tape over the looper thread 17 and the portions of the needle thread loops 13 on the looper side of the bag. This strip 21 extends from one side of the bag to the other and is heat sealed throughout its length to the tape on opposite sides of the threads.

In the manufacture of bags according to this invention, tapes 7 may be applied to bag ends and the bag ends stitched in conventional known manner. Then, the strips 19 and 21 are applied over the stitching, and each strip is heat sealed to the tape by means of any suitable heat-sealing member such as a heated presser bar having a coating of a material such as Teflon (a polymerized tetrafluoroethylene) which prevents the bar from sticking to the strip. As a result of the heat sealing of the strips to the tape, the srips are so deformed that plastic material from the strips is forced into the needle holes, forming plugs as indicated at 23 for the strip 19 and at 25 for the strip 21.

The strips 19 and 21, being heat sealed to the tape, and being keyed to the bag by the plugs 23 and 25, act to prevent the stitches from tearing out through the paper at the end of the bag and thus reinforce the closure. They also close the needle holes and prevent sifting of the bag contents through the needle holes. Under some circumstances where prevention of sitting is the primary object, the sealing strip on the looper side of the bag may be omitted. The strips, in covering the thread, prevent it from becoming scufied and also act to secure any skipped stitches. Since the strips consist of polyethylene or the like, they are unaffected by changes in atmospheric temperature and humidity.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above methods without departing from the scope of the invention in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of forming a closure for an end of a paper bag comprising folding a paper tape around said end of the bag and adhering it to the bag, driving a line of stitching through the tape and through the Walls of the bag to secure together the walls adjacent said end of the bag, applying a separate strip of heat-sealable plastic.

material over the stitching at least on one side of the tape, and applying heat and pressure to the strip to heat seal it throughout its length to the tape on opposite sides of the stitching, and to cause portions of the plastic material of the strip to extend into and plug the needle holes made by the stitching.

2. The method of forming a closure for an end of a paper bag comprising folding a paper tape around said end of the bag and adhering it to the bag, driving a line of stitching through the tape and through the walls of the bag to secure together the walls adjacent said end of the bag, said stitching comprising a needle thread having loops extending rom one side of the bag through the tape and through needle holes in the bag to the other side of the bag and a looper thread on the other side of the bag securing the loops from pulling out through the needle holes, applying a separate strip of heat-scalable plastic material over the needle thread on said one side of the bag, and applying heat and pressure to the strip to 3, heat seal it throughout its length to the tape on opposite sides of the needle thread, and to cause portions of the plastic material of the strip to extend into and plug the needle holes.

3. The method of forming a closure for an end of a paper bag comprising folding a paper tape around said end of the bag and adhering to the bag, driving a line of stitching through the tape and through the Walls of the bag to secure together the Walls adjacent said end of the bag, applying separate strips of heat-sealable plastic material over the stitching on both sides of the tape, and applying heat and pressure to the strips to heat seal them throughout their length to the tape on opposite sides of the stitching, and to cause portions of the plastic material of the strips to extend into and plug the needle holes made by the stitching.

4. The method of forming a closure for an end of a paper bag comprising folding a paper tape around said end of the bag and adhering it to the bag, driving a line of stitching through the tape and through the walls of the bag to secure together the Walls adjacent said end of the bag, said stitching comprising a needle thread having loops extending from one side of the bag through the tape and through needle holes in the bag to the other side of the bag and a looper thread on the other side of the bag securing the loops from pulling out through the needle holes, applying separate strips of heat-sealable plastic material over the needle thread and looper thread on both sides of the bag, and applying heat and pressure to the strips to heat seal them throughout their length to the tape on opposite sides of the threads, and to cause portions ofth-e plastic material of the strips to extend into and plug the needle holes.

References Cited in the file of this patent UNITEDSTATES PATENTS 1,109,515 Dahl Sept. 1, 1914 1,857,949 Freydberg May 10, 1932 2,372,632 Webb Mar. 27, 1945 2,375,544 Faillot May 8, 1945 2,391,946 Clayton Jan. 1, 1946 2,403,756 Read July 9, 1946 2,432,968 Lahey Dec. 16, 1947 2,539,799 Streller Jan. 30, 1951 2,576,933 Geimer et a1. Dec, 4, 1951 2,625,318 Ross Jan. 13, 1953 2,749,966 Roetger June 2, 1956 FOREIGN PATENTS 641,576 Great Britain Aug. 16, 1950 163,494 Australia June 21, 1955 

1. THE METHOD OF FORMING A CLOSURE FOR AN END OF A PAPER BAG COMPRISING FOLDING A PAPER TAPE AROUND SAID END OF THE BAG AND ADHERING IT TO THE BAG, DRIVING A LINE OF STITCHING THROUGH THE TAPE AND THROUGH THE WALLS OF THE BAG TO SECURE TOGETHER THE WALLS ADJACENT SAID END OF THE BAG, APPLYING A SEPARATE STRIP OF HEAT-SEALABLE PLASTIC MATERIAL OVER THE STITCHING AT LEAST ON ONE SIDE OF THE TAPE, AND APPLYING HEAT AND PRESSURE TO THE STRIP TO HEAT SEAL IT THROUGHOUT ITS LENGTH TO THE TAPE ON OPPOSITE SIDES OF THE STITCHING, AND TO CAUSE PORTIONS OF THE PLASTIC MATERIAL OF THE STRIP TO EXTEND INTO AND PLUG THE NEEDLE HOLES MADE BY THE STITCHING. 